Power-factor regulator.



F. H. WINTER.

POWER FACTOR REGULATOR.

APPLICATION FILED AUG-4.1913.

1,165,928. Patented Dec. 28, 1915.

Witnesses Inventor:

UNITED I STATES PATENT OFFICE.

FRED H. WINTER, OI SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION 01' NEW YORK.

POWER-FACTOR REGULATOR.

Specification of Letters Patent.

Patented Dec. 28, 1915.

Application filed August 4, 161a. Serial No. 782,799.

To all whom it may concern Be it known that I, FRED H. citizen of theUnited States, residing at Schenectady, county of Schenectady, State ofNew York, have invented certain new and WINTER, a

. useful Improvements in Power-Factor Regof which the following is aspecithe system. It is well known that, by varycited synchronous machineconnected to an ing the field excitation of a separately exalternatingcurrent distributing system, the phase relation between the current andpotential in the line can be kept practically constant, the necessarywattless current being supplied by this machine. A device designed toautomatically secure this result is illustrated in the patent toTirrill, N 0. 1,084,674.

. The present invention relates especially to improvements in the meansfor regulating the field excitation of such a machine by an apparatus ofthe type illustrated in the Tirrill patent. A

The object of my invention is, then, to improve the construction of sucha power factor regulator so that it shall be quick and accurate in itsoperation.

Another object of my invention is to arrange my regulator so that itshall be unaffected by changes in load upon the system.

In carrying out my invention, I use a modified form of the well-knownTirrill voltage regulator arranged to control the excitation of thefield of a synchronous machine which is connected to the alternatingcurrent system. The construction of my regulator is similar to thatshown in Tirrill $11,084,674, but differs therefrom in the constructionand arrangement of the controlling means which is responsive to thepower factor of the line. In the" construction shown in the Tirrillpatent this controlling means comprises two potential coils coactingwith a floating current coil suspended by means of a stem from thealternating current control lever. In my improved construction I providea pair of cores connected to the alternating current control lever.Associated with these cores are potential windings respectivelyconnected across two mains of the system and arranged to exert opposedmagnetic pulls on said leverv through the medium of the cores. associatewith each of said windings a current winding, the two current windingsbeing connected in parallel and supplied with current from ed in serieswith that main to which both potential windings are joined. The effectof this arrangement is to hasten orretard the time of the closing of themain control contacts in accordance with the fluctuations in phasebetween the current and potential,

as will lie-explained more'fully hereinafter, so as to increase ordecrease the field excita tion of the synchronous motor and therebythrow into the system either a leading or a la%ging wattless current asmay be required.

ince I am only concerned with the relative phase relations of currentand voltage, it is desirable that the effect of the current windingsshould not bevaried by changes in load and hence in the magnitude of thecurrent in the system. I, therefore, provide means for keeping themagnitude of the current in the current windings substantially constantirrespective of the load on the system.

The accompanying drawing is a diagram illustrating an alternatingcurrent system of distribution embodying my invention.

a current transformer connect- I then.

The supply mains 1, 2, 3, of a three phase system furnish current toaload circuit (not shown), and to this system there is also connected asynchronous dynamo-electric machine 5 whose field coil 6 is energized byan exciter' 7. A rheostat 8 in series with the field coil 6 enables themagnetization of the field of the synchronous machine to be ad justed.The circuit of the exciter field coil 9 also contains an adjustableresistor 10 which is shunted by the contacts 11, controlled by the relay12, taking current from the exciter buses 13. The relay is controlled bya pair of floating contacts 14 carried on levers 15, 16, the formerbeing attached to the movable core 17 of a direct current control magnet18 which is connected across the mains of the exciter. The pull of themagnet is opposed by a spring 19. The other lever 16 is attached tocores 20 and 20' which are attached to a stem 20" and move freely up anddown through fixed windings 21, 22,

23 and 24. A dash-pot 2 5 is connected with i 7 cores arecounterbalanced by an adjustable op osed pulls on weight asa shot cup29. The windings 23 and 24 are each connected between a common main: ,ofthe system and another main and are associated respectively with cores20 and 20 in such a manner-that they exert such cores.

suitable non-inductive resistance 26 is inserted in series with windings23 and 24 to reduce the current in such windings,

The windings 21 and 22 are connected in parallel to a currenttransformer 27 and are\its phase displacement with reference to theassociated withand are preferably so wound as. to oppose windings 23 and24 respectively. This current transformer is connected in series withthat main of the system to which both of the potential windings areconnected. With the arrangement so far described satisfactory regulationof v the synchronous motor can be-obtained. I

have found however that as the load on the line increases, thecorresponding increase of current in the windings 21 and 22 tends toaffect the sensitiveness of the regulating contacts, and in order toavoid this I place across the secondary of the current trans-' former ashunt 28 which gives a practically clear that I may so constant drop inpotential for a large range of current flowing through it. Such a shuntmight comprise a boron-carbon filament which is well known to possessthis propert While I have shown and described my cores 20 and 20' asbeing arranged in longitudinal alinement and connected to the stem 20,it will of course'be understood that I am not limited to this specificarrangement as any arrangement whereby the resultant of two opposingpulls can be transmitted to the lever 16 may be used. It will also bedesign my windings 21, 22, 23 and 24 that either the current windings orthe potential windings may be the predominating windings or I. may sodesign them that the resultant atany particular power factor may bezero. In the latter case it will be clear that the weight 29 would thenbe of such value as to just balance the weight of cores 20,20 and thestem 20". The operation is as follows: Suppose that the synchronousmachine is running without load, and the floating control contactsandother parts are adjusted so that the synchronous machine is excited tosuch a value as to give neither-leading or lagging cur-' rent; in otherwords let the power factor of the system be unity. Under theseconditions the weight 29 is adjusted to such a to be in phase with thepotential. In the arrangement as -illustrated, the current in thecurrent coils is leading'the current in potential coil 24 and laggin thecurrent in potential coil 23. If now t e power factor of the systemtends to vary, the current in the current coils'will move more nearlyinto phase with one of the potential coils, while other coil will becomegreater thereby, unbalancing the resultant pull on cores 20, 20 andcauslng the contact carried by the floatcoils 21 and 22 is midway there-Y ing lever 16 to move upward or downward as the-case may be. Forexample, if the current of the system tends to lag then the current inthe current coil 22 comes more nearly into phase with that in potentialcoil 24, thereby decreasing the resultant pull on core 20, while the,current in coil 21 .moves more out of phase with that in potential coil23 thereby increasing the resultant pull on core 20. As a result of thisunbalancing the cores 20, 20 will be lowered thereby raising the contactcarried by lever 16 and as a result increasing the excitation of thesynchronous machine in a manner which iswell understood in connectionwith the operation of the ordinary type of Tirrill voltage regulator soas to throw a leading current into the lines.

While I have assumed. for the purpose of explanation that the powerfactor of-the system was to be kept at unity, itwill of course beunderstood that my system canbe ad usted for, anypower factor desired.It will be seen, then, that by means of my improved construction, I vamable to avoid the use of a moving coil on a stem suspended from one ofthe control levers. This results Further, we are now dealing with theaction of resultant fluxes onassociated cores. The

- space between the fixed coil and the moving core may, therefore, bereduced to a minimum, whereas with the construction using a movable coiladapted to be attracted or re-' pulsed by the interlinkage of linesofforces between it and the fixed coils, there must necessarily be aconsiderable air gap therebetween in order to allow for the .necessarymovement of the coil. Moreover, by the use of my arrangement formaintaining a con-- stant current in the current coils, I obtain uniformaction at all loads and a sensitiveness not otherwise obtainable. I

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In a power factor regulator for a polyphase system, of distributionwhich includes a synchronousdynamo electric machine and a pair ofcontacts for controlling the excitation of said machine, meansresponsive to the power factor of the system for controlling one of saidcontacts, said means comprising connected cores, a potential windingassociated with each core and each connected between a common main andanother main of the system and exerting opposed pulls on said cores, acurrent winding associated with each potential winding and connected inparallel with that main of the system to which both potential windingsare connected, means for maintaining a constant current in said currentwindings and means for transmitting motion from said cores to saidcontact.

2. In a power factor regulator for a threephase system of distributionwhich includes a synchronous dynamo electric machine, a

pair of contacts for controlling the excita-- tion of said machine,means responsive to the power factor of the system for controlling oneof said contacts, said means comprising a pair of connected cores, apotential winding associated with each core and each connected betweentwo mains of the system and exerting opposed pulls on said cores, acurrent winding associated with each potential winding and connected toreceive current from that main of the system i to which both potentialwindings are connected, means for maintaining a constant current in saidcurrent windings, and means for transmitting motion from said cores tosaid contact.

3. In combination, a polyphase system having distributing mains, asynchronous dynamo-electric machine connected thereto, means responsiveto the power factor of said system controlling the excitation of saidmachine, said controlling means comprising a moving contact member,cores attached to said member, a fixed current coil and a fixedpotential coil associated with each core for controlling its movement,and means for maintaining a constant current in said current coils, bothof said current coils being responsive to changes in the phase relationof the current in one of said mains, one of said potential coils beingresponsive to change in the phase relation of the voltage between saidfirst main and a second main, the other of said potential coils beingresponsive to changes in the phase relation of the voltage between thefirst main and a third main.

In witness whereof, I have hereunto set my hand this 2nd day of Au st,1913.

FRED I-I WINTER. Witnesses:

HELEN Onronn, BENJAMIN B. HULL.

